Interpretive Summary: There are questions about the optimal dietary intake to support an ongoing exercise program in typical Americans. The purpose of this investigation was to study the effects of varied levels of dietary carbohydrate and fat intake on exercise training and high intensity exercise performance in moderately strength trained, aerobic trained and untrained males. Subjects (6 strength trained, 6 aerobically trained serving as an active control group, 6 sedentary) consumed isoenergetic diets considered either high CHO/low fat (HC/LF: total energy 62% CHO, 20% fat, 18% protein) or moderate CHO and fat (MC/MF: total energy 42% CHO, 40% fat, 18% protein) in a randomly assigned crossover design. Each dietary treatment was three weeks in length. Prior to the study and following each dietary treatment, muscular strength and endurance was determined. No differences as a result of the dietary treatment were seen in isokinetic peak torque, total work production, single repetition maximum (1 RM) bench press, or number of bench press repetitions at 80% 1 RM. Self-reported exercise log data showed no dietary effect on the subject's ability to maintain training level. These findings indicate that varying dietary macronutrient content (HC/LF or MC/MF) had no effect on exercise training or stength exercise performance in moderately trained (aerobic and strength) or sedentary males. These data will benefit those who plan the diets for soldiers, athletes and those who participate in regular physical activity.

Technical Abstract:
The purpose of this investigation was to study the effects of varied levels of dietary carbohydrate and fat intake on exercise training and high intensity exercise performance in moderately strength trained, aerobic trained and untrained males. Subjects (6 strength trained, 6 aerobically trained serving as an active control group, 6 sedentary) consumed isoenergetic diets considered either high CHO/low fat (HC/LF: total energy 62% CHO, 20% fat, 18% protein) or moderate CHO and fat (MC/MF: total energy 42% CHO, 40% fat, 18% protein) in a randomly assigned crossover design. Each dietary treatment was three weeks in length. Prior to the study and following each dietary treatment, muscular strength and endurance was determined (isokinetic knee extension and flexion, standard concentric free weight bench press). No differences as a result of the dietary treatment were seen in isokinetic peak torque, total work production, single repetition maximum (1 RM) bench press, or number of bench press repetitions at 80% 1 RM. Self-reported exercise log data showed no dietary effect on the subject's ability to maintain training level. These findings indicate that varying dietary macronutrient content (HC/LF or MC/MF) had no effect on exercise training or stength exercise performance in moderately trained (aerobic and strength) or sedentary males.